1. Field of the Invention
The present invention relates to a substrate with a surface-collection-layer and a catalyst-carrying substrate with a surface-collection-layer. More particularly, the present invention relates to a substrate with a surface-collection-layer and a catalyst-carrying substrate with a surface-collection-layer that have a sufficient partition wall strength, a low pressure loss, and a high particulate matter collection efficiency, and may be used for a gasoline direct injection engine.
2. Description of Related Art
Exhaust gas discharged from an internal combustion engine (e.g., diesel engine) or a combustion apparatus (hereinafter may be appropriately referred to as “internal combustion engine or the like”) contains a large amount of particulate matter (hereinafter may be appropriately referred to as “particulate matter”, “particulate” or “PM”) that mainly contains soot (black smoke). If particulate matter is directly discharged to the atmosphere, environmental pollution occurs. Therefore, a filter that collects particulate is generally provided in an exhaust gas passage from an internal combustion engine or the like.
For example, a honeycomb filter 100 (wall-flow type filter) shown in FIG. 7 has been known as a honeycomb filter used for such a purpose (see Patent Document 1, for example). The honeycomb filter 100 includes a honeycomb structure having a plurality of cells 103 (exhaust gas passages) defined by a partition wall 104 formed of a porous ceramic having a number of pores, one open end and the other open end of the cells 103 being alternately plugged by plugging portions 110. According to such a honeycomb filter, when exhaust gas is introduced into the exhaust gas inlet cells, particulate matter contained in the exhaust gas is collected by the partition wall when the exhaust gas passes through the partition wall. The exhaust gas from which particulate matter has been removed (i.e., purified gas) is discharged from the purified gas outlet cells.